JP2015177286A - Multi-frequency common antenna and antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve directivity in a plurality of frequencies which are different, respectively.SOLUTION: A multi-frequency common antenna includes: an antenna body which is resonated in a plurality of frequencies being different, respectively; and a single coaxial feeder which includes an inner conductor and an outer conductor covering an outer periphery and supplies power to the antenna body. The coaxial feeder includes at least two pieces of Spertopf disposed at an outer peripheral side of the coaxial feeder. Each Spertopf includes: a dielectric body disposed in an axial direction of the coaxial feeder; and a conductor which covers an outer periphery of the dielectric body and covers an end portion of the dielectric body at a side opposite to a feeding point side. A length of one of the two pieces of Spertopf in the axial direction of the dielectric body is set to a length of 1/4 wavelength in one of the plurality of frequencies, and a length of the other Spertopf in the axial direction of the dielectric body is set to a length of 1/4 wavelength in another frequency between the plurality of frequencies.

Description

  The present invention relates to a multi-frequency antenna and an antenna device.

  In mobile communication or the like, a plurality of frequency bands such as an 800 MHz band, a 1.5 GHz band, and a 2.0 GHz band are assigned as frequency bands used for communication. For this reason, it is advantageous if one antenna can be shared by a plurality of frequencies. Therefore, the present applicant has already proposed a multi-frequency shared antenna that can share one antenna at a plurality of frequencies (see, for example, Patent Document 1). As such a multi-frequency shared antenna, as shown in FIG. 18, a plurality of antenna elements 102 and 103 are electrically connected to a single coaxial feed line 101, and each antenna element 102 fed from a feed point 104 is connected. Some 103 emit radio waves of different frequencies.

JP 2012-165355 A

However, in the multi-frequency antenna, the current leaking from the feeding point 104 flows along the outer peripheral surface of the outer conductor 101a of the coaxial feeding line 101 and flows in the direction of the arrow in the figure. There is a problem that the flowing current becomes unbalanced and the directivity of each antenna element 102, 103 is distorted.
Therefore, in order to suppress the leakage of current from the feeding point 104, it is conceivable to provide a super top 105 near the feeding point 104 of the coaxial feeding line 101 as shown in FIG. However, since the axial length H ′ of the super top 105 depends on the frequency used, it is difficult to apply to an antenna that requires wideband characteristics such as a multi-frequency shared antenna.

  For example, in the multi-frequency antenna shown in FIG. 19, when there is no super top, the directivity in the 1.5 GHz band is such that the center line P of the main beam is shifted by about 5 ° as shown in FIG. In the directivity in the 2.0 GHz band, as shown in FIG. 20B, the center line P of the main beam is shifted by about 10 °. Consider a case where directivity in both the 1.5 GHz band and the 2.0 GHz band is improved by providing a super power to the coaxial feeder from this state.

  First, when the length H ′ of the super top is set to a length corresponding to the 2.0 GHz band, in the 2.0 GHz band, from the state shown in FIG. 20B, as shown in FIG. The central line P of the main beam becomes 0 °, and the directivity is improved. However, in the 1.5 GHz band, the center line P of the main beam is further shifted to 15 ° as shown in FIG. 21A from the state shown in FIG. 20A, and the directivity is not improved.

  On the contrary, when the length H ′ of the super top is set to a length corresponding to the frequency of the 1.5 GHz band, in the 1.5 GHz band, the state shown in FIG. 20 (A) is changed to the state shown in FIG. 22 (A). As shown, the central line P of the main beam is in a state of about 0 °, and the directivity is improved. However, in the 2.0 GHz band, the center line P of the main beam is shifted by about 5 ° as shown in FIG. 22B from the state shown in FIG. 20B, and the directivity is not improved much. .

  In addition, when the length H ′ of the super top is set to a length corresponding to an intermediate frequency band (for example, 1.7 GHz band) between the 1.5 GHz band and the 2.0 GHz band, From the state shown in FIG. 20A, the center line P of the main beam is further shifted to about 10 ° as shown in FIG. 23A, and the directivity is not improved. Also in the 2.0 GHz band, the center line P of the main beam is shifted by about 5 ° as shown in FIG. 23B from the state shown in FIG. 20B, and directivity is improved. .

  The present invention has been made in view of such problems, and an object of the present invention is to provide a multi-frequency shared antenna and an antenna device that can improve directivity at a plurality of different frequencies.

  The present invention includes an antenna body that resonates at a plurality of different frequencies, and an inner conductor and an outer conductor that covers the outer periphery of the antenna body, and a single coaxial feed line that feeds power to the antenna body. An antenna, comprising at least two supertops disposed on an outer peripheral side of the coaxial feed line, wherein each super top includes a dielectric disposed along an axial direction of the coaxial feed line; A conductor covering an outer periphery of the dielectric and covering an end of the dielectric opposite to a feeding point side, and the dielectric axis of one of the two super tops. The length of the direction is set to ¼ of the wavelength at one frequency among the plurality of frequencies, and the axial length of the dielectric of the other super top is the frequency of the plurality of frequencies. At one other frequency of A multi-band antenna that is set to 1/4 of the length of the long.

  From another viewpoint, the present invention includes a first antenna body that resonates at a plurality of different frequencies, an inner conductor and an outer conductor that covers the outer periphery thereof, and a single first coaxial that feeds power to the first antenna body. A first polarized multi-band antenna for vertical polarization comprising a feed line; a second antenna body that resonates at a plurality of different frequencies; and an outer conductor that covers an inner conductor and an outer periphery thereof; A second multi-frequency common antenna for horizontally polarized waves, and a first multi-frequency common antenna and a second multi-frequency common antenna. Is an antenna device that is disposed so that the positions in the front-rear direction are shifted from each other, and the first and second coaxial feed lines are arranged close to each other, and the first and second coaxial feed lines are At least one of the coaxial feeds At least two super tops disposed on the outer peripheral side of the wire, each super top including a dielectric disposed along an axial direction of the at least one coaxial feed line, and an outer periphery of the dielectric And a conductor covering an end of the dielectric opposite to the feeding point side, and the axial length of the dielectric of one of the two supertops is the dielectric length. , The length of one of the plurality of frequencies is set to ¼ of the wavelength, and the length of the other super-top of the dielectric in the axial direction is the other of the plurality of frequencies. The antenna device is set to a length of ¼ of the wavelength at one frequency.

  According to the present invention, directivity at a plurality of different frequencies can be improved.

1 is a perspective view of a multi-frequency shared antenna according to a first embodiment of the present invention. It is a side view of a multi-frequency common antenna. It is a front view of an antenna main body. FIG. 4 is an enlarged view of a main part of FIG. 3 showing connection portions between the first and second lines and the first antenna element. It is a cross-sectional schematic diagram which shows the edge part by the side of the feeding point of a coaxial feeder. (A) is the directivity of the second antenna element in the 1.5 GHz band, and (B) is the directivity of the second antenna element in the 2.0 GHz band. (A) is the directivity in the 700 MHz band of the first antenna element, and (B) is the directivity in the 800 MHz band of the first antenna element. It is a cross-sectional schematic diagram which shows the modification of a super top. It is a cross-sectional schematic diagram which shows the modification of the super top of FIG. It is a cross-sectional schematic diagram which shows the other modification of a super top. It is a perspective view of the multi-frequency common antenna which concerns on 2nd Embodiment of this invention. It is a side view of the multifrequency shared antenna of the second embodiment. It is a front view of the antenna main body of 2nd Embodiment. It is a perspective view of the antenna device which concerns on 3rd Embodiment of this invention. It is a side view of the antenna apparatus which concerns on 3rd Embodiment. It is a front view of the reflective element of 3rd Embodiment. It is a schematic diagram which shows the conventional balun. It is a perspective view of the conventional multi-frequency common antenna. It is a perspective view of the multi-frequency common antenna provided with the conventional super top. (A) is the directivity of the 1.5 GHz band when there is no conventional super top, and (B) is the directivity of the 2.0 GHz band when there is no conventional super top. (A) is the directivity of the 1.5 GHz band when the conventional super top is set to a length corresponding to the 2.0 GHz band, and (B) is the conventional super top compatible with the 2.0 GHz band. The directivity of the 2.0 GHz band when the length is set. (A) is the directivity of the 1.5 GHz band when the conventional super top is set to a length corresponding to the 1.5 GHz band, and (B) is the conventional super top compatible with the 1.5 GHz band. The directivity of the 2.0 GHz band when the length is set. (A) is the directivity of the 1.5 GHz band when the conventional super top is set to a length corresponding to the intermediate frequency band, and (B) is the length corresponding to the conventional super top corresponding to the intermediate frequency band. This is the directivity of the 2.0 GHz band when set to the above.

[Description of Embodiment of the Present Invention]
First, the contents of the embodiment of the present invention will be listed and described.
(1) A multi-frequency shared antenna according to an embodiment of the present invention includes an antenna body that resonates at a plurality of different frequencies, an inner conductor and an outer conductor that covers the outer periphery thereof, and a single power feeding to the antenna body. A multi-frequency shared antenna comprising at least two super tops disposed on an outer peripheral side of the coaxial power feed line, wherein each super top is provided on the coaxial power feed line. A dielectric disposed along the axial direction; and a conductor covering an outer periphery of the dielectric and covering an end of the dielectric opposite to the feeding point side, The axial length of the dielectric of one super top is set to ¼ of the wavelength at one frequency of the plurality of frequencies, and the dielectric of the other super top The axial length of the It is set to 1/4 of the length of the wavelength at another frequency of the frequency.

  According to the multi-frequency antenna, at least two super tops are arranged on the outer periphery of the coaxial feeder, and the axial length of the dielectric in each super top is a length corresponding to a different frequency. Since it is set, it is possible to suppress leakage of current corresponding to each frequency from the feeding point by each super top. As a result, directivity at a plurality of different frequencies can be improved.

(2) Preferably, the two super tops of (1) are stacked in the outer direction of the coaxial feeder.
In this case, the axial arrangement space of the super top can be reduced.

(3) It is preferable that, of the two super tops of (2), the super top with the shorter axial length of the dielectric is disposed on the outside.
In this case, each super top can be easily manufactured as compared with the case where the super top having the longer axial length of the dielectric is disposed outside.

(4) It is preferable that the two super tops of the above (2) or (3) are arranged with the end faces on the feeding point side of the respective dielectrics aligned at positions close to the feeding point.
In this case, current leakage from the feeding point can be effectively suppressed.

(5) The two super tops of (1) may be arranged with their axial positions shifted from each other.
In this case, it is possible to easily manufacture each super top as compared with the case where two super tops are stacked in the outer direction of the coaxial feeder.

(6) An antenna device according to an embodiment of the present invention from another viewpoint includes a first antenna body that resonates at a plurality of different frequencies, an inner conductor, and an outer conductor that covers an outer periphery thereof, and the first antenna. A first multi-frequency shared antenna for vertically polarized waves, and a second antenna body that resonates at a plurality of different frequencies, an inner conductor, and an outer periphery thereof. A second multi-frequency shared antenna for horizontally polarized waves having an outer conductor covering the first antenna body and a single second coaxial feed line that feeds power to the second antenna body. The frequency sharing antenna and the second multi-frequency sharing antenna are arranged with their positions shifted from each other in the front-rear direction, and the first and second coaxial feed lines are arranged close to each other, 1st and 2nd coaxial feed And at least two super tops disposed on the outer peripheral side of at least one of the coaxial power supply lines, and each super top is disposed along an axial direction of the at least one coaxial power supply line. A dielectric and a conductor that covers an outer periphery of the dielectric and covers an end of the dielectric opposite to a feeding point side, and of the two super tops, The axial length of the dielectric is set to ¼ of the wavelength at one of the plurality of frequencies, and the axial length of the dielectric of the other super top is The length is set to ¼ of the wavelength at the other one of the plurality of frequencies.
According to the antenna device, the same effect as the multi-frequency shared antenna of (1) can be obtained.

[Details of the embodiment of the present invention]
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[First Embodiment: Horizontally Polarized Antenna]
[overall structure]
FIG. 1 is a perspective view of a multi-frequency antenna 1 according to the first embodiment of the present invention. FIG. 2 is a side view of the multi-frequency shared antenna 1. The multi-frequency antenna 1 of this embodiment is suitably used as an antenna (transmission / reception antenna) of a base station that performs wireless communication with a mobile terminal such as a mobile phone. In addition, although the multi-frequency shared antenna 1 of this embodiment is for horizontal polarization, it can also be used for vertical polarization.

  The multi-frequency shared antenna 1 includes an antenna body 10 having a plurality of antenna elements (radiating elements) 11, 12, a single coaxial feed line 20 that feeds a feeding point 15 of the antenna body 10, and the antenna body 10. And a pair of first parasitic elements 40 provided on the front side of the antenna body 10. In the present embodiment, in the Z-axis direction to be described later, the positive direction (upper side in FIG. 2) is “front side” and the negative direction (lower side in FIG. 2) is “rear side” (others described later) The same applies to the embodiment).

The reflecting plate 30 includes a main reflecting plate 30a and a pair of sub-reflecting plates 30b arranged on the front side of both side edges of the main reflecting plate 30a and perpendicular to the main reflecting plate 30a. The sub-reflecting plate 30b is fixed to the main reflecting plate 30a by a set screw (not shown).
The coaxial power supply line 20 is arranged so as to reach the power supply point 15 from the main reflector 30a, and flows in a state where signals of a plurality of frequencies are mixed. At the end of the coaxial feeder 20 on the feeding point 15 side, a plurality of super tops 25 and 26 described later are provided.
As shown in FIG. 1, in this specification, the direction in which the coaxial power supply line 20 extends is the Z-axis direction, the direction along the sub-reflecting plate 30b of the reflecting plate 30 is the X-axis direction, and the X-axis direction and the Z-axis direction. A direction orthogonal to both directions is defined as a Y-axis direction.

  Two or more types of antenna elements 11 and 12 are provided in order to resonate at four frequencies of 700 MHz, 800 MHz, 1.5 GHz, and 2.0 GHz and radiate radio waves of those frequencies. Among them, the second antenna element 12 is arranged inside the first antenna element 11 and resonates at two high frequencies (1.5 GHz band and 2.0 GHz band). The first antenna element 11 resonates at two other low frequencies (700 MHz band and 800 MHz band). The antenna body 10 may be configured by a single antenna element that resonates at a plurality of different frequencies, such as the second antenna element 12 of the present embodiment.

  Each antenna element 11, 12 has a first antenna part 111, 121 and a second antenna part 112, 122. The first antenna units 111 and 121 and the second antenna units 112 and 122 corresponding to the first antenna units 111 and 121 are arranged so as to be aligned in the polarization direction with the feeding point 15 in between, and are formed symmetrically with each other. Here, in this embodiment, the “polarization direction” is a direction in which an electric field vibrates when radio waves are radiated from the antenna elements 11 and 12 (the same applies to other embodiments described later). This is the Y-axis direction.

FIG. 3 is a front view of the antenna body 10. As shown in FIGS. 2 and 3, the antenna elements 11 and 12 constituting the antenna body 10 are formed on a planar substrate 10a. The first antenna portions 111 and 121 of the antenna elements 11 and 12 are formed on the front surface (one surface) 10a1 of the substrate 10a, and the second antenna portions 112 and 122 are formed on the rear surface (other surface) 10a2 of the substrate 10a. Yes. The rear surface 10a2 of the substrate 10a is a connection surface to which the coaxial feeder 20 is connected.
Note that the first antenna portions 111 and 121 and the second antenna portions 112 and 122 may be formed in the reverse side of the substrate 10a, or may be formed collectively on either side of the substrate 10a.

  The substrate 10a is supported at a predetermined interval from the main reflecting plate 30a by a support portion 50 attached to the main reflecting plate 30a. In FIG. 1, the substrate 10a and the support portion 50 are omitted.

[First antenna element]
Of the two antenna elements 11 and 12, the first antenna portion 111 of the first antenna element 11 corresponding to a low frequency (700 MHz band and 800 MHz band) is formed from a pair of dipole elements bent so that the tips are close to each other. Become. The pair of dipole elements 111 are formed symmetrically with respect to each other across a virtual line K including the feeding point 15 and extending in the polarization direction. Each dipole element 111 includes a straight portion 111b that extends straight in the polarization direction, a bent portion 111a that is bent at a right angle inward from the tip of the straight portion 131b, and an inclination from the base end of the straight portion 111b to the straight portion 111b. And an inclined portion 111c that is bent in such a manner. The inclined portion 111c is formed so that the separation distance L in the polarization direction between the second antenna portion 112 and the inclined portion 112c (described later) gradually increases as the distance from the feeding point 15 side increases toward the linear portion 111b side. ing. The dipole element 111 is bent as a whole, but may be formed in a straight line, or may be formed in an arc or an ellipse.

The second antenna portion 112 of the first antenna element 11 is formed symmetrically with the first antenna portion 111 with the center line C interposed therebetween. That is, the second antenna portion 112 is composed of a pair of dipole elements, and each dipole element 112 is composed of a bent portion 112a, a straight portion 112b, and an inclined portion 112c. Here, the center line C is a line that passes through the feeding point 15 and extends in a direction orthogonal to the polarization direction in the same plane and bisects each antenna element 11 and 12 in the polarization direction.
Since the bent portion 112a, the straight portion 112b, and the inclined portion 112c have the same configuration as the bent portion 111a, the straight portion 111b, and the inclined portion 111c of the first antenna portion 111, detailed description thereof is omitted. In addition, although the antenna elements 11 and 12 of this embodiment are both configured by dipole elements, some or all of them may be configured by loop antenna elements formed in a loop shape.

  The antenna main body 10 extends from the feeding point 15 toward the first antenna units 111 and 121, and is connected to the first antenna units 111 and 121. A pair of second lines 17 extending toward the antenna portions 112 and 122 and connected to the second antenna portions 112 and 122 are provided. The first line 16 and the second line 17 are formed symmetrically with respect to the center line C.

  FIG. 4 is an enlarged view of a main part of FIG. 3 showing each connection portion between the first and second lines 16 and 17 and the first antenna element 11. As shown in FIG. 4, the line width D1 of the first line 16 is formed narrower than the element width Wb1 of the straight portion 111b in the first antenna portion 111 of the first antenna element 11 in order to increase the impedance. Yes. Similarly, the line width D2 of the second line 17 is formed narrower than the element width Wb2 of the linear portion 112b in the second antenna portion 112 of the first antenna element 11 in order to increase the impedance.

  The inclined portion 111c in the first antenna portion 111 of the first antenna element 11 is connected to the straight portion 111b that is a portion along the polarization direction from the connection end portion 111c1 with the first line 16 on the feeding point 15 side. The element width Wc1 is gradually increased as it goes. Thereby, the element width Wb1 of the portion (straight line portion 111b) along the polarization direction of the first antenna portion 111 of the first antenna element 11 is equal to the feeding point 15 side (connection end portion 111c1) of the first antenna portion 111. It is thicker than the element width Wc1.

  Like the inclined portion 111c, the inclined portion 112c of the second antenna portion 112 of the first antenna element 11 extends along the polarization direction from the connection end portion 112c1 with the second line 17 on the feeding point 15 side. The element width Wc2 is formed so as to gradually increase toward the straight line portion 112b which is a portion. Thereby, the element width Wb1 of the portion (straight line portion 112b) along the polarization direction of the second antenna portion 112 of the first antenna element 11 is the element on the feeding point 15 side (connection end portion 112c1) of the second antenna portion 112. It is thicker than the width Wc1.

As described above, since the element width of the portion of the first antenna element 11 along the polarization direction of each of the antenna portions 111 and 112 is larger than the element width on the feeding point 15 side, two first antenna elements 11 are provided. The bandwidth for resonating at frequencies (700 MHz band and 800 MHz band) can be widened.
Further, the antenna portions 111 and 112 of the first antenna element 11 of the first antenna element 11 are formed so that the element width gradually increases from the feeding point side toward the portion along the polarization direction. Therefore, the transmission mode can be gradually converted from the feeding point 15 side of each antenna unit 111, 112 toward the portion along the polarization direction.

[Second antenna element]
Of the two antenna elements 11 and 12, the first antenna part 121 of the second antenna element 12 corresponding to a high frequency (1.5 GHz band and 2.0 GHz band) is bent in such a manner that the tips are bent toward each other. Dipole element. The pair of dipole elements 121 are formed in line symmetry with respect to the virtual line K. Each dipole element 121 includes a straight portion 121b that extends straight in the polarization direction, and a bent portion 121a that is bent at a right angle inward from the tip of the straight portion 121b.

  The second antenna portion 122 of the second antenna element 12 is formed symmetrically with the first antenna portion 121 with the center line C interposed therebetween. That is, the second antenna unit 122 includes a pair of dipole elements, and each dipole element 122 includes a bent portion 122a and a straight portion 122b. Since the bent part 122a and the straight part 122b have the same configuration as the bent part 121a and the straight part 121b of the first antenna part 121, detailed description thereof is omitted.

[First parasitic element]
As shown in FIGS. 1 and 3, the pair of first parasitic elements 40 provided on the front side of the antenna body 10 straddle the center line C, and the first and second antenna portions 111 of the first antenna element 11. , 112 and the linear portions 121b, 122b of the first and second antenna portions 121, 122 of the second antenna element 12 are arranged extending in the polarization direction. The first parasitic element 40 is formed on the substrate 41 as shown in FIG. The substrate 41 is supported at a predetermined interval from the substrate 10a by a support portion 42 attached to the front surface 10a1 of the substrate 10a on which the antenna body 10 is formed. The first parasitic element 40 is disposed on the front side of the antenna body 10, but may be disposed on the rear side of the antenna body 10.

[Coaxial feeder]
FIG. 5 is a schematic cross-sectional view showing an end portion of the coaxial feeder 20 on the feeding point 15 side. As shown in FIG. 5, the coaxial feeder 20 is formed of a coaxial cable, and includes an inner conductor 20a, an insulator 20b that covers the outer periphery thereof, and an outer conductor 20c that covers the outer periphery of the insulator 20b. The end portion of the inner conductor 20a penetrates the substrate 10a (see FIG. 2) in the thickness direction and is electrically connected to the end portion 16a of the first line 16. On the other hand, the end portion of the outer conductor 20 c is electrically connected to the end portion 17 a of the second line 17. Thereby, both end portions 16 a and 17 a of the first and second lines 16 and 17 constitute a feeding point 15 of the antenna body 10.

[Super Top]
On the outer peripheral side of the coaxial power supply line 20, a first spar top 25 and a second spel top 26 are provided for suppressing current leakage from the power supply point 15 along the outer peripheral surface of the outer conductor 20 c. . In the present embodiment, these two super tops 25 and 26 are stacked in the outer direction of the coaxial feeder 20.
The first super top 25 is a cylindrical first dielectric 25a fixed to the outer peripheral surface of the outer conductor 20c of the coaxial feeder 20 and a bottomed cylindrical first covering the outer periphery of the first dielectric 25a. And a conductor 25b.
The second super top 26 is a cylindrical second dielectric 26a fixed to the outer peripheral surface of the first conductor 25b of the first super top 25, and a bottomed cylindrical shape covering the outer periphery of the second dielectric 26a. Second conductor 26b.

The first dielectric 25a of the first super top 25 is made of, for example, Teflon (registered trademark) and extends in the axial direction of the coaxial feeder 20 (the Z-axis direction in the drawing; hereinafter, also simply referred to as “axial direction”). Are arranged along. The axial length H1 of the first dielectric 25a is set to ¼ of the wavelength of the 1.5 GHz band, which is the lower frequency of the two frequencies at which the second antenna element 12 resonates. Yes. Here, the “1/4 length” of the wavelength in the 1.5 GHz band is not only the same length as 1/4 of the wavelength, but also slightly shorter than 1/4 of the wavelength, and the wavelength It is meant to include the case where it is slightly longer than ¼. The end face 25a1 on the feeding point 15 side of the first dielectric 25a is disposed at a position close to the feeding point 15.
The first conductor 25b of the first super top 25 includes an outer wall portion 25b1 that covers the outer peripheral surface of the first dielectric 25a, and an annular bottom wall portion that covers the end surface of the first dielectric 25a opposite to the feeding point 15 side. 25b2. The inner peripheral end of the bottom wall portion 25b2 is fixed in contact with the outer peripheral surface of the outer conductor 20c.

Similar to the first dielectric 25a, the second dielectric 26a of the second super top 26 is made of, for example, Teflon (registered trademark), and is disposed along the axial direction. The second dielectric 26a is arranged such that the end surface 26a1 on the feeding point 15 side is aligned with the end surface 25a1 of the first dielectric 25a. The axial length H2 of the second dielectric 26a is set to ¼ of the wavelength of the 2.0 GHz band, which is the higher frequency of the two frequencies at which the second antenna element 12 resonates. Yes. Here, “the length of ¼” of the wavelength in the 2.0 GHz band is not only the same length as ¼ of the wavelength, but also slightly shorter than ¼ of the wavelength, and the wavelength It is meant to include the case where it is slightly longer than ¼.
Thus, since the axial length H2 of the second dielectric 26a is set based on a wavelength having a frequency higher than the axial length H1 of the first dielectric 25a, the length H2 is greater than the length H1. Set to a short length. Therefore, in this embodiment, the shorter one of the two sper tops 25 and 26 in the axial direction of the dielectric is disposed outside.

The second conductor 26b of the second super top 26 includes an outer wall portion 26b1 that covers the outer peripheral surface of the second dielectric 26a and an annular bottom wall portion that covers the end surface of the second dielectric 26a opposite to the feeding point 15 side. 26b2. The inner peripheral end of the bottom wall portion 26b2 is fixed in contact with the outer peripheral surface of the first conductor 25b.
Note that the super tops 25 and 26 may correspond to two frequencies (700 MHz band and 800 MHz band) at which the first antenna element 11 resonates. The number of super tops is not limited to two, and three or more may be provided corresponding to three or four frequencies out of a total of four frequencies at which the antenna body 10 resonates. . Furthermore, the first dielectric 25a and the second dielectric 26a may be formed of a dielectric material such as ceramics other than Teflon (registered trademark) or air.

  With the above configuration, a part of the current corresponding to the frequency in the 1.5 GHz band flows into the first dielectric 25a from the feeding point 15 through the outer conductor 20c, as indicated by an arrow e1 in the figure. By reciprocating the length H1 in the axial direction, a length of 1/2 (= 1/4 + 1/4) of the wavelength of the 1.5 GHz band flows. For this reason, the phase of the current flowing through the path indicated by the arrow e1 is reversed when it reciprocates inside the first dielectric 25a and returns to the end face 25a1. On the other hand, among the currents corresponding to the frequency in the 1.5 GHz band, as indicated by the arrow e2 in the figure, the current flowing on the end face 25a1 of the first dielectric 25a from the feeding point 15 via the outer conductor 20c. Remain in phase. Therefore, it is possible to suppress the leakage of current from the feeding point 15 by causing the current that flows in the opposite direction through the path indicated by the arrow e1 and the current in the same phase that flows through the path indicated by the arrow e2 to cancel each other.

  Similarly, a part of the current corresponding to the frequency in the 2.0 GHz band flows into the second dielectric 26a from the feeding point 15 through the outer conductor 20c, as indicated by an arrow e3 in the figure, By reciprocating the length H2 in the axial direction, a length of 1/2 (= 1/4 + 1/4) of the wavelength in the 2.0 GHz band flows. For this reason, the phase of the current flowing through the path indicated by the arrow e3 is reversed when the current travels back and forth in the first dielectric 25a and returns to the end face 26a1. On the other hand, among the currents corresponding to the frequency in the 2.0 GHz band, as indicated by the arrow e4 in the figure, the current flowing on the end face 25a1 of the first dielectric 25a from the feeding point 15 via the outer conductor 20c. Remain in phase. Therefore, it is possible to suppress the leakage of the current from the feeding point 15 by the current flowing in the opposite direction through the path indicated by the arrow e3 and the current flowing in the same direction flowing through the path indicated by the arrow e4 cancel each other.

FIG. 6A shows the directivity in the 1.5 GHz band of the second antenna element 12 of the present embodiment. FIG. 6B shows the directivity in the 2.0 GHz band of the second antenna element 12 of the present embodiment. In the directivity in the 1.5 GHz band of FIG. 6 (A), the center line P of the main beam is in a state of 0 ° as compared with the case without the super top in FIG. You can see that it has improved. Further, in the directivity in the 2.0 GHz band of FIG. 6B, the center line P in the front direction of the main beam is in a state of about 0 ° as compared with the case without the super top of FIG. It can be seen that the directivity is improved.
FIG. 7A shows the directivity in the 700 MHz band of the first antenna element 11 of the present embodiment. FIG. 7B shows the directivity in the 800 MHz band of the first antenna element 11 of the present embodiment. As shown in FIGS. 7A and 7B, in the 700 MHz band and the 800 MHz band, the center line P of the main beam does not deviate much from 0 °, and these frequencies are caused by the super tops 25 and 26. It can be seen that there is almost no influence on the directivity in the.

  As described above, according to the multi-frequency shared antenna 1 of the first embodiment, the two super tops 25 and 26 are arranged on the outer periphery of the coaxial feeder 20, and the dielectrics 25 a and 26 a in the super tops 25 and 26 are arranged. Since the axial lengths H1 and H2 are set to lengths corresponding to different frequencies (1.5 GHz band and 2.0 GHz band), each super top 25, 26 corresponds to each frequency. Current flowing through the feed point 15 can be suppressed. As a result, directivity at different frequencies can be improved.

In addition, since the two super tops 25 and 26 are stacked in the outer direction of the coaxial feeder 20, the axial arrangement space of the super tops 25 and 26 can be reduced.
Moreover, since the super top 26 whose axial length is shorter among the two super tops 25 and 26 is disposed on the outside, the dielectric is formed as shown in FIGS. Compared to the case where the spar top 25 having the longer axial length is disposed outside, each spar top 25, 26 can be easily manufactured.

  Further, since the two super tops 25 and 26 are arranged with the end faces 25a1 and 26a1 on the feeding point 15 side of the dielectrics 25a and 26a aligned at positions close to the feeding point 15, as described above. The phase of the current flowing from the feeding point 15 into each of the dielectrics 25a and 26a can be reliably reversed by reciprocating in the axial direction. Thereby, it is possible to effectively suppress current leakage from the feeding point 15.

  In addition, the second conductor 26b of the second super top 26 is electrically connected to the outer conductor 20c of the coaxial feeder 20 via the first conductor 25b of the first super top 25. As shown, the structure of the second super top 26 can be simplified as compared with the case where the second conductor 26b is directly connected to the outer conductor 20c. Thereby, the 2nd super top 26 can be manufactured still more easily.

[Modification of Super Top]
FIG. 8 is a schematic cross-sectional view showing a modification of the super top. In this modification, the second supper top 26 is disposed on the inner side, and the first sperle top 25 is disposed on the outer side. Specifically, the second dielectric material 26 a of the second super top 26 is fixed to the outer peripheral surface of the outer conductor 20 c of the coaxial feeder 20. The end face 26 a 1 on the feeding point 15 side of the second dielectric 26 a is disposed at a position close to the feeding point 15.
The second conductor 26b of the second super top 26 includes an outer wall portion 26b1 that covers the outer peripheral surface of the second dielectric 26a and an annular bottom wall portion that covers the end surface of the second dielectric 26a opposite to the feeding point 15 side. 26b2. The inner peripheral end of the bottom wall portion 26b2 is fixed in contact with the outer peripheral surface of the outer conductor 20c.

The first dielectric 25a of the first super top 25 is fixed to the outer peripheral surface of the second conductor 26b with the end face 25a1 on the feeding point 15 side aligned with the end face 26a1 of the second dielectric 26a. .
The first conductor 25b of the first super top 25 includes an outer wall portion 25b1 that covers the outer peripheral surface of the first dielectric 25a, and an annular bottom wall portion that covers the end surface of the first dielectric 25a opposite to the feeding point 15 side. 25b2 and an inner wall portion 25b3 that covers the lower end portion of the inner peripheral surface of the first dielectric 25a that projects downward from the second super top 26 in the drawing. The upper end of the inner wall portion 25b3 in the figure is fixed in contact with the lower end of the outer wall portion 26b1 of the second conductor 26b in the drawing.

FIG. 9 is a schematic cross-sectional view showing a modification of the super top in FIG. In this modification, the lower end portion of the first super top 25 in the figure is in contact with and fixed to the coaxial feeder 20. Specifically, the first dielectric 25a of the first super top 25 has a cylindrical portion 25a2 formed along the axial direction and an annular portion 25a3 extending inward from the lower end of the cylindrical portion 25a2 in the drawing. ing. The inner peripheral end of the annular portion 25a3 is fixed in contact with the outer peripheral surface of the outer conductor 20c.
The first conductor 25b of the first super top 25 includes an outer wall portion 25b1 that covers the outer peripheral surface of the first dielectric 25a, and a lower end surface in the figure of the annular portion 25a3 of the first dielectric 25a (on the feeding point 15 side). And an annular bottom wall portion 25b2 that covers the opposite end surface. The inner peripheral end of the bottom wall portion 25b2 is fixed in contact with the outer peripheral surface of the outer conductor 20c.

  FIG. 10 is a schematic cross-sectional view showing another modification of the super top. In this modified example, the first sperl top 25 and the second sperl top 26 are arranged with their axial positions shifted from each other. Specifically, the second dielectric 26a of the second super top 26 is fixed to the outer peripheral surface of the outer conductor 20c of the coaxial feeder 20 with its end face 26a1 disposed at a position close to the feeding point 15. Yes. The inner peripheral end of the bottom wall portion 26b2 of the second conductor 26b of the second super top 26 is fixed in contact with the outer peripheral surface of the outer conductor 20c.

The first sperle top 25 is arranged at a predetermined interval on the lower side in the figure with respect to the second sperle top 26. The first dielectric 25 a of the first super top 25 is fixed to the outer peripheral surface of the outer conductor 20 c of the coaxial feeder 20. The inner peripheral end of the bottom wall portion 25b2 of the first conductor 25b of the first super top 25 is fixed in contact with the outer peripheral surface of the outer conductor 20c.
As described above, in the case of this modified example, the two super tops 25 and 26 are arranged so as to be shifted from each other in the axial direction, so that compared to the case where they are stacked in the outer direction of the coaxial feeder 20. Thus, each super top 25, 26 can be easily manufactured. In addition, the position of the axial direction may be arrange | positioned reversely at the 1st sperl top 25 and the 2nd sperl top 26.

[Second Embodiment: Vertically Polarized Antenna]
[overall structure]
FIG. 11 is a perspective view of the multi-frequency antenna 1 according to the second embodiment of the present invention. FIG. 12 is a side view of the multi-frequency shared antenna 1. The antenna body 10 of the multi-frequency shared antenna 1 according to this embodiment has three antenna elements 11, 12, and 13. The multi-frequency antenna 1 of the present embodiment is for vertical polarization, but can also be used for horizontal polarization.

  As shown in FIG. 11, there are three types of antenna elements 11, 12, and 13 because they resonate at four frequencies of 700 MHz, 800 MHz, 1.5 GHz, and 2.0 GHz and radiate radio waves at those frequencies. Is provided. Among them, the second and third antenna elements 12 and 13 are arranged on the inner side of the first antenna element 11 and resonate at a high frequency of 1.5 GHz band and 2.0 GHz band, respectively. . The first antenna element 11 is configured to resonate at the other two low frequencies (700 MHz band and 800 MHz band) as a single unit.

  Each antenna element 11, 12, 13 has a first antenna part 111, 121, 131 and a second antenna part 112, 122, 132. The first antenna units 111, 121, 131 and the corresponding second antenna units 112, 122, 132 are aligned in the polarization direction (X-axis direction in this embodiment) with the feeding point 15 in between. They are arranged and formed symmetrical to each other.

[First antenna element]
FIG. 13 is a front view of the antenna body 10 including the antenna elements 11, 12, and 13. As shown in FIG. 13, among the plurality of antenna elements 11, 12, and 13, the tips of the first antenna portions 111 of the first antenna element 11 corresponding to low frequencies (700 MHz band and 800 MHz band) are close to each other. It consists of a pair of dipole elements bent into two. The pair of dipole elements 111 are formed symmetrically with respect to each other across a virtual line K including the feeding point 15 and extending in the polarization direction. Each dipole element 111 includes a straight portion 111b that extends straight in the polarization direction, a bent portion 111a that is bent at a right angle inward from the tip of the straight portion 131b, and an inclination from the base end of the straight portion 111b to the straight portion 111b. And an inclined portion 111c that is bent in such a manner. The inclined portion 111c is formed so that the separation distance L in the polarization direction between the second antenna portion 112 and the inclined portion 112c (described later) gradually increases as the distance from the feeding point 15 side increases toward the linear portion 111b side. ing.

  The second antenna portion 112 of the first antenna element 11 is formed symmetrically with the first antenna portion 111 with the center line C interposed therebetween. That is, the second antenna portion 112 is composed of a pair of dipole elements, and each dipole element 112 is composed of a bent portion 112a, a straight portion 112b, and an inclined portion 112c. Since the bent portion 112a, the straight portion 112b, and the inclined portion 112c have the same configuration as the bent portion 111a, the straight portion 111b, and the inclined portion 111c of the first antenna portion 111, detailed description thereof is omitted.

  The antenna body 10 extends from the feeding point 15 toward the first antenna units 111, 121, 131, and is connected to the first antenna units 111, 121, 131. And a pair of second lines 17 that extend toward the second antenna portions 112, 122, and 132 and are connected to the second antenna portions 112, 122, and 132. The first line 16 and the second line 17 are arranged so as to overlap in the front-rear direction in the front view of FIG.

[Second antenna element]
Among the plurality of antenna elements 11, 12, 13, the first and second antenna parts 121, 122 of the second antenna element 12 corresponding to the frequency of 1.5 GHz band are bent so that the tips approach each other. Dipole element. The pair of dipole elements 121 and 122 are formed in line symmetry with respect to the virtual line K. Each of the dipole elements 121 and 122 includes straight portions 121b and 122b that extend straight in the polarization direction, and bent portions 121a and 122a that are bent at a right angle from the front end of the straight portion 121b.

[Third antenna element]
Among the plurality of antenna elements 11, 12, 13, the first antenna portion 131 of the third antenna element 13 corresponding to the highest frequency (2.0 GHz band) is a pair of dipoles whose ends are bent so as to approach each other. It consists of elements. The pair of dipole elements 131 are formed in line symmetry with respect to the virtual line K. Each dipole element 131 includes a straight portion 131b that extends straight in the polarization direction, and a bent portion 131a that is bent at a right angle from the front end of the straight portion 131b. Each straight portion 131b is arranged so as to intersect with the bent portion 121a of the antenna portion 121 of the second antenna element 12 at the intermediate portion 131b1. As a result, the base end side of each straight line portion 131b is positioned closer to the inner side than the antenna portion 121 of the second antenna element 12, and is arranged in close contact with the straight portion 121b of the antenna portion 121. ing. In addition, the distal end side of each straight line portion 131b with respect to the intermediate portion 131b1 is disposed outside the antenna portion 121 of the second antenna element 12.

  The second antenna portion 132 of the third antenna element 13 is formed symmetrically with the first antenna portion 131 with the center line C interposed therebetween. That is, the second antenna portion 132 is composed of a pair of dipole elements, and each dipole element 132 is composed of a bent portion 132a and a straight portion 132b. Each straight part 132b is arranged so as to intersect with the bent part 122a of the antenna part 122 of the second antenna element 12 at the intermediate part 132b1. Since the bent part 132a and the straight part 132b have the same configuration as the bent part 131a and the straight part 131b of the first antenna part 131, detailed description thereof is omitted.

Although the plurality of antenna elements 11, 12, and 13 of the present embodiment are all configured by dipole elements, some or all of them may be configured by loop antenna elements formed in a loop shape. Good.
Moreover, although the antenna element 11 of this embodiment respond | corresponds to two frequencies, you may make it provide two antenna elements respectively corresponding to these each frequency. In this case, the two antenna elements may be arranged so that a part of the antenna elements cross each other like the second antenna element 12 and the third antenna element 13 of the present embodiment.

[First and second parasitic elements]
As shown in FIGS. 12 and 13, the pair of first parasitic elements 40 provided on the front side of the antenna body 10 straddle the center line C, and the first and second antenna portions 121 of the second antenna element 12. , 122 are arranged so as to cover the respective straight portions 121b, 122b. On the front surface 10a1 of the substrate 10a, a pair of second parasitic elements 45 are arranged outside the antenna portions 111 and 112 of the first antenna element 11, respectively. The pair of second parasitic elements 45 are arranged symmetrically with respect to each other in a direction orthogonal to the polarization direction across the feeding point 15.

  Each second parasitic element 45 is arranged outside the straight portions 111b and 112b of the antenna portions 111 and 112 at a predetermined interval and extends in the polarization direction across the center line C. By providing the pair of second parasitic elements 45, the first antenna element 11 can improve the return loss characteristic in the 700 MHz band while maintaining the return loss characteristic in the 800 MHz band.

[Super Top]
On the outer peripheral side of the coaxial power supply line 20, a first spar top 25 and a second spel top 26 are provided for suppressing current leakage from the power supply point 15 along the outer peripheral surface of the outer conductor 20 c. . The axial length H1 (see FIG. 5) of the first dielectric 25a in the first super top 25 is 1.5 GHz band which is the lower frequency of the two frequencies at which the second antenna element 12 resonates. The length is set to 1/4 of the wavelength. Further, the axial length H2 (see FIG. 5) of the second dielectric 26a in the second super top 26 is 2.0 GHz which is the higher of the two frequencies at which the third antenna element 13 resonates. The length is set to ¼ of the band wavelength.
In addition, the point which abbreviate | omitted description in 2nd Embodiment is the same as that of 1st Embodiment.

[Third Embodiment: Horizontal / Vertical Polarization Antenna]
[overall structure]
14 and 15 show an antenna device 60 corresponding to horizontal polarization and vertical polarization according to the third embodiment of the present invention. The antenna device 60 is functionally equivalent to a combination of the multi-frequency shared antenna 1 of the second embodiment and the multi-frequency shared antenna 1 of the first embodiment. That is, the antenna device 60 is a combination of the first multi-frequency antenna 1-1 for vertical polarization and the second multi-frequency antenna 1-2 for horizontal polarization, with the positions in the front-rear direction being shifted. It is.

When only the single reflector 30 is provided when the vertically polarized antenna body 10 (first antenna body) and the horizontally polarized antenna body 10 (second antenna body) are shifted in the front-rear direction, An interval between one of the two antenna bodies 10 and 10 and the reflecting plate 30 becomes inappropriate. Therefore, the antenna device 60 of the present embodiment includes a reflective element 31 that functions as a reflective plate separately from the reflective plate 30.
The reflector 30 functions as a reflector for all the antenna elements 11, 12, 13 of the vertically polarized antenna body 10 and the first antenna element 11 of the horizontally polarized antenna body 10.

  FIG. 16 is a front view of the reflective element 31. As shown in FIGS. 15 and 16, a pair of reflecting elements 31 are formed on the substrate 33 with a predetermined interval. Each reflective element 31 is formed to extend in the polarization direction so as to be arranged behind the straight portions 121b and 122b of the second antenna element 12 for horizontal polarization. Thereby, the pair of reflection elements 31 functions as a reflection plate of the second antenna element 12 for horizontal polarization. Note that a vertically polarized coaxial feed line 20 (first coaxial feed line) and a horizontally polarized coaxial feed line 20 (second coaxial feed line) pass between the pair of reflecting elements 31 on the substrate 33. A through-hole 33a is formed for placement.

  As shown in FIG. 15, the antenna device 60 is configured by arranging a reflective element 31, a vertically polarized antenna body 10, and a horizontally polarized antenna body 10 in this order on the front side of the reflector 30. Yes. Note that the vertically polarized antenna body 10 and the horizontally polarized antenna body 10 may be disposed in the reverse direction. In this case, the reflective element 31 is disposed so as to be along the polarization direction of the vertically polarized antenna body 10 disposed on the front side by changing the longitudinal direction of the reflective element 31 by 90 degrees. It functions as a reflector of the first antenna element 11.

  The substrate 33 on which the reflective element 31 is formed is supported by the first support part 51 from the reflective plate 30 at a predetermined interval. The substrate 10 a of the vertically polarized antenna body 10 is supported from the substrate 33 by the second support portion 52 at a predetermined interval. Further, the substrate 10 a of the horizontally polarized antenna body 10 is supported by the third support part 53 from the vertically polarized substrate 10 a at a predetermined interval. In FIG. 14, the substrates 10a and 33 and the first to third support portions 51 to 53 are omitted.

  As shown in FIG. 15, the coaxial feed lines 20 for vertically polarized waves and horizontally polarized waves are arranged close to each other. The coaxial feed line 20 of the vertically polarized multi-frequency antenna 1-1 is arranged so as to pass through the substrate 33 from the reflector 30 to the feed point 15 of the vertically polarized antenna body 10. . The coaxial feeding line 20 of the horizontally polarized multi-frequency antenna 1-2 passes through the substrate 33 and the vertically polarized substrate 10a from the reflector 30 and feeds the feed point 15 of the horizontally polarized antenna body 10. It is arranged to reach.

[Super Top]
Two super tops 25 and 26 are provided at the end of the coaxial feed line 20 for vertical polarization and horizontal polarization on the feed point 15 side, respectively. In addition, the super tops 25 and 26 may be provided only in any one of the both coaxial feed lines 20 for vertical polarization and horizontal polarization. Further, in the third embodiment, points that are not described are the same as those in the first and second embodiments.

  Incidentally, as a conventional structure for suppressing current leakage from the feeding point of the antenna, there is a balun 70 as shown in FIG. The balun 70 includes a metal support 72 that is arranged in parallel to the coaxial feed line 71 and electrically connected to the inner conductor 71a of the coaxial feed line 71, and an outer conductor 71b and the metal support 72 of the coaxial feed line 71. And a short-circuit conductor 73 for short-circuiting. In the illustrated example, antenna elements 74 and 75 are connected to the outer conductor 71b and the metal support 72 of the coaxial feeder 71, respectively.

However, as in the present embodiment, the vertically polarized antenna 1-1 and the horizontally polarized antenna 1-2 are arranged with their positions shifted in the front-rear direction, and both antennas 1-1, 1- In the antenna device 60 in which the coaxial feed lines 20 that feed power to 2 are arranged close to each other, a large space cannot be secured near each coaxial feed line 20. For this reason, even if it is going to employ | adopt the said balun 70 for the antenna apparatus 60, the space which arrange | positions the metal support | pillar 72 in each coaxial feeding line 20 for vertical polarization and horizontal polarization cannot be ensured.
On the other hand, in this embodiment, since the plurality of super tops 25 and 26 are provided in each coaxial power supply line 20, current leakage can be suppressed in a smaller space than the balun 70. Therefore, in the structure in which the plurality of super tops 25 and 26 are provided, like the antenna device 60 of the present embodiment, the coaxially feeding wires 20 for vertical polarization and horizontal polarization are arranged close to each other, and the balun 70 is arranged. This is particularly effective when it cannot be adopted. In the present embodiment, the vertical feed and horizontal polarization coaxial power supply lines 20 are provided with super tops 25 and 26, but at least one of the coaxial power supply lines 20 is provided with a super top. It should be.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Multi-frequency common antenna 1-1 1st multi-frequency common antenna 1-2 2nd multi-frequency common antenna 10 Antenna main body 10a Board | substrate 10a1 Front surface 10a2 Rear surface 11 1st antenna element 111 1st antenna part 111a Bending part 111b Straight line part 111c Inclination Part 111c1 Connection end part 112 Second antenna part 112a Bend part 112b Straight part 112c Inclined part 112c1 Connection end part 12 Second antenna element 121 First antenna part 121a Bend part 121b Straight part 122 Second antenna part 122a Bend part 122b Straight part 13 Third antenna element 131 First antenna portion 131a Bending portion 131b Straight portion 131b1 Intermediate portion 132 Second antenna portion 132a Bending portion 132b Straight portion 132b1 Intermediate portion 15 Feed point 16 First line 17 Second line 20 Coaxial feed line 20a Inner conductor 20b Insulator 20c Outer conductor 25 First super top 25a First dielectric 25a1 End face 25a2 Cylindrical part 25a3 Annular part 25b First conductor 25b1 Outer wall part 25b2 Bottom wall part 25b3 Inner wall part 26 Second super top 26a Second dielectric substance 26a1 End face 26b Second conductor 26b1 Outer wall portion 26b2 Bottom wall portion 30 Reflector 30a Main reflector 30b Sub reflector 31 Reflector 33 Substrate 33a Through hole 40 First parasitic element 41 Substrate 42 Support section 45 Second parasitic element 50 Support Part 51 First support part 52 Second support part 53 Third support part 60 Antenna device 70 Balun 71 Coaxial feed line 71a Inner conductor 71b Outer conductor 72 Metal support 73 Short-circuit conductor 74 Antenna element 75 Antenna element C Center line D1 Line width D2 Line width H1 Length H2 Length K Virtual line L Separation distance Wb1 Element width Wb2 Element width Wc1 Element Child width Wc2 Element width

Claims (6)

An antenna body that resonates at different frequencies,
A multi-frequency shared antenna comprising an inner conductor and an outer conductor covering the outer periphery thereof, and a single coaxial feeder for feeding power to the antenna body,
Comprising at least two super-tops arranged on the outer peripheral side of the coaxial feeder;
Each of the super tops includes a dielectric disposed along the axial direction of the coaxial power supply line, and a conductor that covers an outer periphery of the dielectric and covers an end of the dielectric opposite to the power feeding point side. Have
The axial length of the dielectric of one of the two supertops is set to a quarter of the wavelength at one frequency of the plurality of frequencies, The multi-frequency shared antenna in which the axial length of the dielectric of the other super top is set to ¼ of the wavelength at the other one of the plurality of frequencies.   The multi-frequency antenna according to claim 1, wherein the two super tops are stacked in an outer direction of the coaxial feeder.   The multi-frequency shared antenna according to claim 2, wherein, of the two super tops, the super top having the shorter axial length of the dielectric is disposed outside.   4. The multi-frequency shared antenna according to claim 2, wherein the two super tops are arranged such that end faces of the dielectrics on the feeding point side are aligned at positions close to the feeding point. 5.   The multi-frequency shared antenna according to claim 1, wherein the two super tops are arranged with their axial positions shifted from each other. A first antenna body that resonates at a plurality of different frequencies,
A first multi-frequency shared antenna for vertically polarized waves, including an inner conductor and an outer conductor covering the outer periphery thereof, and a single first coaxial feed line that feeds power to the first antenna body;
A second antenna body that resonates at a plurality of different frequencies,
A second multi-frequency shared antenna for horizontally polarized waves, including an inner conductor and an outer conductor covering the outer periphery thereof, and a single second coaxial feed line that feeds power to the second antenna body. ,
The first multi-frequency common antenna and the second multi-frequency common antenna are arranged with their positions in the front-rear direction shifted, and the first and second coaxial feed lines are antenna devices arranged close to each other. There,
Comprising at least two super tops disposed on the outer peripheral side of at least one of the first and second coaxial feeders;
Each of the super tops covers a dielectric disposed along the axial direction of the at least one coaxial feed line, an outer periphery of the dielectric, and an end of the dielectric opposite to the feed point side. A conductor,
The axial length of the dielectric of one of the two supertops is set to a quarter of the wavelength at one frequency of the plurality of frequencies, The antenna device in which the axial length of the dielectric of the other super top is set to ¼ of the wavelength at the other one of the plurality of frequencies.

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